Single line telegraph repeater



Oct. 24, 1939. F. G. HALLDEN SINGLE LINE TELEGRAPH REPEATER Filed D90.28, 1937 m I II-IlnI OCM Patented Oct. 24, 1939 UNITED STATES PATENT@FFME SINGLE LINE TELEGRAPH REPEATER Application December 28, 1937,Serial No. 182,140

14 Claims.

My invention relates to single line telegraph repeaters and particularlysingle line repeaters provided with means for repeating polar controlledsignals.

Single line telegraph systems with a wire line with ground return havebeen used for interconnecting printer stations. In these systems thesignals are generally composed of two types of elements only, eithercurrent impulses of opposite polarity or current impulses of onepolarity with spaces or periods of no current. If the lines are so shortthat no re-enforcing of the signals by repeating is necessary a thirdtype of signal elements may be introducedfor other control purposes,that is a spacing interval in the double polarity system or an impulseof reverse polarity in the single polarity make-break system.

When repeaters are used in a single line system, however, theconstruction and limitations are such that repeating of the three typesof signal elements cannot be readily accomplished. It isy desirable,however, to provide a means for signalling different stations forestablishing a con nection, or for remotely starting a motor at astation even when a repeater is included in the system. Such signals maycomprise an impulse of reverse polarity in addition to the regularsignalling impulses and spacings of a make-break Ysignalling system.

Itis an object of my invention to provide single line repeaters capableof repeating normal signals comprising impulses of one polarity andspaces, and reverse polarity signals.

It is a further object of. my invention to providea means whereby motorcontrol signals may be repeated. overa single line repeater in additionto message signals.

It is a still further object of my invention to device a system which iscapable of repeating message signals and also reverse polarity sig-knals, for the purpose ofr motor control. or other purposes, for use in atelegraph circuit.

Other objects and advantages of my invention will present themselvesfrom a reading of the particular. description given in connection withthe accompanying. drawing, in which Fig.. 1 illustrates one embodimentof my invention. applied to a simple printer exchange system,.and

Fig. 2 discloses another modification of my invention which isparticularly adapted for use in one form of automatic switching printertelegraph arrangements.

'Iurning now to Fig. 1,v there is shown a telegraph system in its normalidle condition. In the idle condition, negative battery extends througha Winding of line relay I, and springs of jack 2 to line 3. At therepeater station line section 3 extends through the armature and irontcontact of repeating relay 4, winding of polar relay 5, and winding ofrepeating relay 6 to ground. Relays I, 5 and 5 will be operated asshown.

Negative battery will also extend through a iront contact and armatureof polar relay 5, Winding of repeating relay contacts of relay 6 overline section I to the distant station and then through printer magnets8, keyboard contacts 9, polar relay I (I, motor control relay II andbreak key I8 to ground. Relays 4, I0 and II will be operated as shown.Contacts of relay II will be held open, interrupting the power sourcefor operation of printer motor I2.

As shown, the power source for printer motor I3 at the central stationwill be open at contacts of relay I4 which is deenergized.

lIf now, printer cord plug I5 is inserted in jack 2, relay I4 willoperate in series with a winding of relay I, thereby starting printermotor I3. Positive battery will now extend through keyboard contacts I6,printer magnets Il, plug I5, and tip spring of jack 2 to line section 3and then to ground through relays 5 and 6 as traced before. Thisreversal of battery through polar re lay 5 will cause its armature toengage its back contact, thereby reversing the current through thecircuit including line section 1 and the station set. This reversalcauses polar relay I0 to move its armature against its back contact,short circuiting the winding of motor control relay II, which releasesand permits it contacts to extend power to motor I2 starting the motor.

The armatures of polar relays 5 and I0 will bear against their backcontacts when positive battery is connected to lines 3 and 'l as justdescribed. Due to the action of the bias springs (not shown) attached tothese armatures, they will also bear against their back contacts when nobattery is connected to lines 3 and 1.

Printer communication may now be carried on between the stations,signals sent by keyboard contacts I6 being repeated by relay 6 and thosesent by keyboard contacts 9 being repeated by relay 4.

The operation of the single line repeater for repeating neutral signalsmay be clearly seen from the drawing. For example, the positive impulsesoriginating at I6 operate relay 6 so as to open line l, the holdingcircuit for relay 4, however, being maintained from positive batterythrough the make-before-break contact of relay 5 to ground. For acomplete description of the operation of such a single line repeaterreierence is made to the patent to G. S. Vernam et al., No. 1,895,015issued on January 24:, 1933.

Removal of plug i5 from jack 2 will reconnect line 3 to negative batterythrough line relay l. Polar relay 5 will operate to engage its frontcontact, thereby reconnecting line 'I toy negative battery. Polar relaylil will disengage its back contact removing the shunt from winding ofrelay I I, which will operate and then its contacts thereby stoppingmotor I2. The circuit will then be restored to its normal idlecondition.

In the idle condition, momentary depression of Y break key i8 will openline 7, releasing relay 4 which will in turn open line 3, causingdeenergization of line relay l. When released, one pair of contacts ofthis relay short circuit the line winding, preventing it from operatingupon reclosure of the line. The other contacts light calling lamp 9through an obvious circuit. This lighted' lamp serves as an indicationat the central station that the outlying station is calling. Toestablish communication, the procedure outlined above shall be followed,merely inserting plug l 5 in jack 2.

A somewhat different arrangement is necessary ior providing a similarreverse current control through a repeater interconnecting outlyingstations when a normally low value reverse current is maintained for thepurpose of automatic switching.

Fig. 2 illustrates an arrangement of a repeater in accordance with myinvention applied to an automatic telegraph switching` system such asdisclosed in the patent to G. S. Vernam No. 1,895,113,

patented January 24, 1933. In this arrangement a printer stationdesignated generally at 300 is connected' through a repeater 205 and aswitching means itil to a central printer apparatus designated generallyat 550. In this arrangement, at the central station is provided aprinter 50' cong trolled by a polar relay 5I, a calling dial 52 and athree-position key 53. Normally current from positive battery flowsthrough the lower winding of re1ay5l while the other upper winding isconnected from ground through upper contact of key element 55, printercontacts and resistance 58 to battery. Relay 5l is differentially woundand the` current through the lower winding is normally about half thatthrough the upper winding.. Negativecurrent is impressed on the linethrough the selective switching means from battery 57 through the lowercontact of switch element 54. From selective vswitching means 450 runtwo lines 40 and 4l. In the normal idle condition, lines 40 and 4| arenot selected and consequently relay 42 is notenergized. A negativebattery is connected through the winding of slow release relay 43, backcontact of relay 42 to a line 2), over line 20, through winding of relay22, contact of relay 23, and windings of relays 24 and 25 to ground.Relays 23 and 24 are the repeating relays, similar to relays ll and 6 ofFig. l; each of these relays,

however, has an additional winding. Relay 25' 21 through line 2i to thestation set 300, through the upper slow resistance and lower highresistance windings of polar relay 30, the lower contact 3l of key 34and the printer apparatus to ground. Current through relay 30 holds itoperated thus maintaining the printer motor 35 at rest.

If communication between the main station 500 and the subscribersstation 300 is desired', the operator at central station 500 dials thenumber corresponding to the station 300. If the station is not busy theselective switching means 400 establishes a circuit, operating relay 42.Operation of relay 42 switches line 25 to the upper contact connectedwithI line l l, extending positive battery from station 560 through theline connection to line 20. This reversal of current over line 20 causespolar relay 25 to move its armature against its back Contact, therebyextending positive bat- Y tery over line 20 to the station set.Simultaneously the pesitivebattery now connected to theY ar- Y,

mature of relay 25 will cause polar'relay 28 to The operation of relay2'! short circuits the lower high resistance winding of polar relay 25.Positive kbattery is now extended over line 2l and since resista-nce 26Yhas been short circuited this battery is strong enough to cause theoperationof relays at station 300. Positive current through relaywinding 30 causes pelar relay 30 to make its backV contact, energizingVrelay 3,6 over a circuit extending'from power supply through the windingof relay 2E, the oli-normal contact of dial 31,1oack contact of relay38, armature of relay 30'to the other side of the power supply.Energization of relay 36 closes the circuit of printer motor 35, causingit to operate. Intercommunication may nowbe carried on between station300 and central station 500, the repeating relays 23 and'24r Operationof relay 22 causes its front contact to make, short circuitingresistance 26.

operating as single line repeaters for the printer signals. Y

When rcommunication is terminated the operator at the central stationoperates a release key, releasing the selective switching means. Releaseof this switching means releases relay 42, connecting line 20 throughwinding of relay 43` to negative battery. This negative batteryextending to the repeater operates relays 25, causing it to disengageitsback contact and to engage its front contact, therebyV connectingnegative battery again to line 2| and tothe station'. set.

Negative battery at the station set operates relay 30, causingritA toopen its contact, stopping'the printer motor at this set. Polar relay'28also disengages its back contact, releasing relays 22 and 2l',V andengages its front contact, reestablishing the circuit for the addedwindings of relays 23 and 24, holding theserelays in the operatedposition. The circuit is now restored to its normal idle condition. V

To initiate a call from the station 3070 to the central station 500,calling key 34 is operated to its calling position, to the right asshown inthe drawing', closing the upper contact 3l and opening its lowercontact. This operates to short circuit the' lower high resistancewinding of polar relay 3l), increasing the current in line 2l. Theincrease in current in line 2l is suiiicient to operatev relay 2l, whichcloses its contact, short circuiting the high resistance winding ofpolar relay 25. The short circuiting of the high resistance winding ofrelay 25 causes an increase in the current in line 2li, causing linerelay t3 to operate. Relay 43 starts the idle selector switches, causingthe line finder to switch the call through to` central station 56d. Whenthe line iinder switch has connected line 2! to an idle selectorcircuit, a current strong enough to operate relay 22 will cause a shortcircuiting of resistor 26, in turn increasing the current in line 2l sothat the dial lamp at that station will light. Dial 3l may then beoperated to select the desired class of service in a manner such asdisclosed in Patenty 1,895,113. These dial pulses will be repeated byrelay 23 to line 2Q. If no selecting circuit is idle at the time theline finder switch connects tol line 2li, the current in line 2D willnot be suiilcient to operate relay 22 and resitor 25 will not be shortcircuited. The current in line 2l will therefore not increasesuiiiciently to light the dial lamp at the station set. When aconnection is nnally establishedv through the switching unit, positivebattery will extend from the station 5GB over line 2i! as previouslyexplained, anc? will condition the circuit for intercommunication andstart the printer motor at station set B as fully described above. Sincemy invention relates only lto the repeater circuit, a completedescription of the operation of the system illustrated in the stationset 390 and the switching means at central stations Mlil and 5%, has notbeen set forth in detail. For a more complete description of theoperation of this part of the system, reference may be had to thedescription in the patent to G. S. Vernam, No. 1,895,113.

While I have described the reverse current control in connection withFigs. l and 2 for the use of starting and stopping printer motors, it isclear that the reverse current may be used for selective signaling, orother purposes. When used for selective signaling the polar relays atthe station set may be used to operate single stroke bells instead ofprinter motors. My invention relates primarily to the repeater circuitfor repeating these reverse current signals regardless of the use thatis made thereof at the printer station.

While only two specic embodiments of my invention have been described inconnection with the accompanying drawing, it should be distinctlyunderstood that these speciiic arrangements are described merely by wayof illustration and not as a limitation on the scope of the invention.What I consider as my invention and desire to secure protection on isdeiined in the appended claims.

I claim:

1. A single line telegraph repeater comprising means for repeatingmessage signals composed of current impulses of one polarity and breakintervals of no current and means for repeating reverse currentimpulses, said last named means comprising a means responsive to thepolarity of applied signals and a contact means controlled thereby.

2. A single line telegraph repeater comprising line controlled relayscontrolling make-break contacts for repeating signals composed ofelements comprising current impulses of one polarity and no currentperiods, and a polar controlled relay controlling a potential reversingmeans for repeating reverse polarity signals.

3. A telegraph system comprising a first station, a second station, asingle transmission line f interconnecting said stations, means fortransmitting signals composed of impulses 0I" one polarity no currentspaces, a repeater in said transmission line between said stations forrepeating said signals, means for transmitting signals of a reversepolarity with respect to said one polarity to said repeater from saidstations, and means in said repeater responsive to said reverse polaritysignals for repeating said reverse polarity signals from said stationtransmitting said signals to said other station.

4f. A single line telegraph repeater comprising a line section, a secondline section, neutral line relays in said rst and second line sections,repeating contacts in each line section controlled by the line relay theother line section for remake-break signals from one line section to theother, means for normally maintaining a current of a fixed polarity onsaid second line section, means responsive to reversal of po- 6. Atelegraph repeater comprising a rst line section, a neutral line relayin said first line section, a second line section, a neutral line relayin said second line section, front contact means in each of said linesections controlled by the relay in the other line section, back contactmeans operative upon opening of said front contact means, to complete aholding circuit for the line relay in the corresponding line section,means for applying a potential to said rst line section, means forreversing the potential applied to said first line section, and meanscontrolled by the polarity applied to said iirst line section forapplying a holding potential of the same polarity to said back contacts.

'7. A telegraph repeater according to claim 6 further comprising meansfor reversing the polarity on said second line section in response tothe reversal of polarity on said rst line section.

8. A telegraph repeater according to claim 6,'

in which said last named means comprises a polar relay connected to saidiirst line section and a circuit controlled by said polar relay.

9. In a telegraph system, a iirst line, a second line, a repeaterconnected between said first and second lines, means' at said repeaterfor normally maintaining a potential of fixed polarity on said iirstline, means for normally maintaining a potential of a fixed polarity onsaid second line, means for reversing the polarity of the potentialapplied to said rst line, and means at said repeater responsive to thesaid reversal of polarity for correspondingly reversing the polarity ofthe potential applied to said second line.

l0. A telegraph repeater comprising a rst line section, a second linesection, separate line relays in each of said line sections, contacts ineach line section controlled by the line relay in the other linesection, holding windings on said line relays, means normallymaintaining a holding potential on said holding windings, means fornormally maintaining a potential of a xed polarity on said second linesection, means responsive to reversal of the potential on said `iirstline section for reversing the potential on said second line section andother means responsive to said reversal of potential for releasing saidholding potential from said holding windings.

1l. In a printer telegraph system, a central station, a subscribersstation, a repeater, a first transmission linev interconnecting saidcentral station and said repeater, a second transmission lineinterconnecting said repeater and said subscribers station, means atsaid repeater for normally maintaining a potential of a xed polarity onsaid second transmission line, means at said central station fornormally maintaining a potential of the same polarity on said firsttransmission line, a separate line relay at said repeater in each ofsaid transmission lines', a contact in each of said transmission linescontrolled by the relay in the other transmission line, means at s'aidsubscribers station for transmitting call signals through said repeaterto said central station, means at said central station for indicatingsaid call signals, means for applying a potential of a reverse polarityon said first transmission line in response to an answer to said callsignals and means at said repeater responsive to said reversal ofpolarity for reversing the polarity of the potential applied to saidsecond line section. Y

12. In a printer telegraph system according to claim 11, a selectiveswitching means at said central stations, and means' responsive to saidcall signals for connecting said subscribers line to said centralstation, said means for applying reverse polarity comprising meansresponsive to said line connection for connecting a reverse polaritysource to said line.

13.k In a printer telegraph system, a central station, a subscribersstation, a repeater, a rst transmission line interconnecting saidcentral station and said repeater, a second transmission lineinterconnecting said repeater and said subscribers station, means atsaid repeater for normally maintaining a potential of a fixed polarityon said second transmission line, means at said central station fornormally maintaining a potential of the same polarity on said rsttransmission line, a separate line relay at said repeater in each ofsaid transmission lines, a contact in each of said transmission linescontrolled by the relay in the other transmission line, means at saidcentral station for applying a reverse polarity on said iirsttransmission line, means at said repeater responsive to said reversal ofpolarity for reversing the polarityof the potential applied to saidsecond line, and means at said subscribers station responsive to saidkpotential reversal for rendering operative said subscribers' printingapparatus.

14. In a printer telegraph system, a central station, a subscribersstation,.a repeater, a rst transmission line interconnecting saidcentral station and said repeater, a second transmission lineinterconnecting said repeater and'said subscribers station, means atsaid repeater for normally maintaining a potential of a xed polarity onsaid second transmission line, means' at said central station fornormally maintaining a potential of the same polarity on said rsttransmission line, a separate line relay at said repeater in each ofsaid transmission lines, a contact in each of said transmission linescontrolled by the relay -in the other transmissionV line, means at saidsubscribers stationV for transmitting call signals through said repeaterto said centralistation, means for applying a potential of a reverse Ypolarity on said transmission line in response to an answer to said callsignals, and means at said repeater responsive to reversal Yof `polarityfor reversing the polarity of the potential applied to said second linesection.

FREDERICK G. HALLDEN.

